<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
    <script>
        $(function() {
            $("#btn").on('click', function() {
                var json = {
                    "width": 500,
                    "height": 500,
                    "left": 300,
                    "top": 300,
                    "border-radius": 100
                };
                var json2 = {
                    "width": 100,
                    "height": 100,
                    "left": 100,
                    "top": 100,
                    "border-radius": 100,
                    "background-color": "red"
                };

                $("div").animate(json, 1000, function() {
                    $("div").animate(json2, 1000, function() {
                        alert("动画执行完毕！");
                    });
                });
            })
        });
    </script>
    <style>
        #d01 {
            width: 100px;
            height: 100px;
            background-color: aqua;
            position: absolute;
        }
        
        #btn {
            position: absolute;
            top: 150px;
        }
    </style>
</head>

<body>
    <div id="d01"></div>
    <button id="btn">开始动画</button>
</body>

</html>